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89 Cards in this Set

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What is sterilization
estruction of all forms of microbes--cells, endospores and viruses

but, not necessarily destruction of toxins (proteins)
Sterilization is the destruction of all forms of microbes. Name three microbes
cells, endospores, and viruses
Sometimes, sterilization does not destruct _____
toxins (proteins)

if have bacterium with toxin, even though kill it, parts (toxins) may still be around
What is disinfection?
killing, inhibition, or removal of pathogens from inanimate objects. Disinfectants can be phyical (UV, heat) or chemical (lysol)
Disinfection is the killing, inhibition, or removal of pathogens from ______
inanimate objects
Antisepsis is the destruction of pathogens on _____
living tissue
Antiseptics (which carry out antisepsis) are almost always ____
chemical
What is sanitization?
Reduction of microbial populations to levels safe according to public health standards
What are four factors to determining the effectiveness of an antimicrobial agent?
population size
population composition
exposure time
local environment
In population composition, microorganisms differ in _______
their sensitivity to various agents

Mycobacterium tuberculosis has mycolic acid in cell wall. Because Mycobacterium tuberculosis has mycolic acid in it, it is harder to get rid of compared to E. coli
_______ has mycolic acid in cell wall. Because it has mycolic acid in it, it is harder to get rid of compared to E. coli.
Mycobacterium tuberculosis
Mycobacterium tuberculosis has ______ in the cell wall
mycolic acid
With exposure time, the _____ exposure, the more microbes killed
longer
A _____ pH makes heat more effective
low (acidic environment)
_____ can protect pathogens
organic matter
(organic matter on top of pathogens make it hard to kill)
What are the two factors under local environment that determine the effectiveness of an antimicrobial agent?
- low pH makes heat more effective
- organic matter can protect pathogens
A microbe is dead when it ____
cannot grow anymore
death of a microbial population is _____
exponential

(example of death rate: 90% every minute)
Name three mechanisms of death
- alteration of membrane permeability
- damage to proteins and nucleic acids
- removal of water
altering membrane permeability could lead to death. Membrane damage causes _______, affects cell growth
cell leakage
damage to proteins and nucleic acids leads to death. Brakage of DNA or denaturation of proteins by chemical and physical agents will disrupt _______ and _____
replication and metabolism
What are two types of physical control?
heat
direct flame
WHy is heat a good type of physical control?
fast, reliable, cheap
Is dry heat more or less effective than moist heat?
less effective

think: stockton vs. boston
What kind of heat is required for powders or oils?
dry heat
direct flame leads to ___
incineration
Give an example of an organism that requires incineration.
Bacillus anthracis (causes anthrax)
What is thermal death time?
the time it takes to kill a microbe at a given temperature

ex: TDT (thermal death time) for tubercle bacilli is 30'@58oC but only 2'@72oC
A hot air oven radiates ____heat at 160oC
dry heat
a hot air oven kills by ______ reactions (alters proteins) and ______
oxidation reactions (alters proteins) and removal of water
hot air ovens are used for powders, oils, glassware. It takes ___ hours to kill spores
2
What is good about the hot air oven?
It does not corrode or erode
Why is moist heat better than dry heat?
water molecules conduct heat better than air
What is the degree Celcius limit of boiling water?
100 oC
How does boiling water kill?
kills by denaturing proteins (ex: egg cahnges color after cooking)
Why is boiling water not considered a sterilization agent?
no guarantee that spores are killed
If you boil water for ten minutes, what is killed?
vegetative cells
If you boil water for 30 minutes, what is killed?
protozoal cysts, fungal spores, large concentrations of hepatitis A virus
If water is boiled 120 minutes or more, what is killed?
bacterial spores (but some spores can survive boiling water for hours)
Autoclave (121.5oC) requires _____minutes for sterilization of most vegetative cells and endospores
15-30

An autoclave creates hot moist air under pressure up to 121.5oC. It kills most everything in 30 minutes
Is pasteurization sterilization?
Pasteurization is NOT sterilization
Pasteurization is ____ to high temperature to reduce microbial population and to increase shelf life
brief exposure
Pasteurization is brief exposure to high temperature to _____ and to ____
reduce microbial population and to increase shelf life
In pasteurization, what is not affected?
spores
pasteurization is aimed at destroying waht?
most heat resistant organisms
Pasteurization is aimed at destroying most heat resistant organisms. Name two of them
Mycobacterium tuberculosis and Coxiella burnetii (agent of Q fever)
What is LTLT?
low temperature, long term pasteurization

30', 62.9oC
What is HTST?
high temperature, short term
FLASH PASTEURIZATION
15s, 71.6oC
What is ultrapasteurization?
like flash pasteurization but at an extreme

3s, 82oC
Hot Oil technique of destroying microbes is used for ___ minutes at ____oC
60'
160oC
Hot Oil is used by some dentists and physicians for _____
sterilization of metal instruments
What is good about hot oil?
it does not corrode or erode metal
What is bad about hot oil?
oil has to be cleaned off after treatment, contamination may be reintroduced
filtration removes microorganisms by ____, _____, or _____
screening, entrapment, or adsorption
There are several types of filters. Name three
organic filters
membrane
HEPA

organic filters are advantageous because the organic molecules of the filter attract organic components in microorganisms. It uses a substance called diatomaceous earth. This material contains the remains of marine algae known as diatoms.
The membrane filter consists of?
cellulose acetate, nitrocellulose or

- (top) nylon membrane with E. coli (can keep E.coli out)
- (bottom) polycarbonate w/ Leptospira

*cellulose acetate, polycarbonate*
HEPA
high efficiency particulate air filter
HEPA removes ____% of particles larger than ____
99.9%
0.3 um
What is the advantage of filters?
can be put on a plate and counted
What is the disadvantages of filters?
expensive, time-consuming, often get clogged
What are the disadvantages of membrane filters?
- flammable (nylon membrane)
- physical limitations (mud --> get clogged)
UV light induces ___
thymine dimers
UV light induces thymine dimers. Mutations occur randomly, sometimes in important genes. It is good for ____
surface sterilization
When it comes to spores, gram ____ are less susceptible to UV light than gram _____
positives
negatives
What are two forms of ionizing radiation?
x-rays, gamma rays
ionization radiation have a shorter wavelengths than UV light. IT forces electrons out of shells and creates
ions
ionizing radiation destroys ____
nucleic acids, proteins
ionizing radiation is used for ______
heat-sensitive materials (pharmaceuticals, plastics)

* waves will kill pathogen but not chemical structure of drug
_____ is FDA approved for food use. It can kill Trichinella spiralis
Cobalt-60
Cobalt-60 is FDA approved for food use. It can kill ____
Trichinella spiralis
What bacterium can survive 1000x more radiation than humans?
deinococcus radiodurans
What do microwaves do?
move water molecules
With microwaves, other than heat or dessication, there is no ____
no specific activity against microoranisms
Laser is _____ by stimulated emission of radiation
light amplification
Laser is light amplification by _____
stimulated emission of radiation
With laser, concentrated light will destroy microbes instantly. WHat is the problem with laser?
coverage is a problem
Ultrasonic vibrations are microscopic bubbles caused by ____
high frequency sound
ultrasonic vibrations is also known as ____
'cold boiling'
In ultrasonic vibrations, the formation and implosion of bubbles is known as _____
cavitation
Some dentists and jewelers use ____
cavitrons
ultrasonic vibrations always requires ___
liquid
what happens with ultrasonic vibrations?
1) high frequency sound waves cause microscopic bubbles to form in the fluid
2) As the bubbles collapse, shock waves are created in the fluid
3) alternating high and low-pressure areas impinge upon microorganisms and destroy them.
What are three preservation methods?
-dessication
-salting or sugaring
-low temperature
dessication. no water, no ___
life

(bread vs. pretzels)
salting or sugaring has to do with ___
osmotic pressure (water diffuses out with salt or sugar on the outside)

problematic: molds can tolerate high sugar (if make jams, jellies, find mold on top)
What is the problem with the sugaring technique of preservation?
molds can tolerate high sugar
low temperature lowers _____ of microorganisms
metabolic rate
low temperature reduces ___
growth rate
What is a problem with the preservation method of low temperature?
some will remain alive at low temperature and start growing fast once out of low temperature